Not Just for Women

Human mitochondrial DNA (mtDNA) is a circular structure composed of 16,569 nucleotides, also referred to as base pairs. It is speculated that mitochondria were originally parasitic bacteria in the human cell structure and just became a normal part of it over time.

Mitochondria, or ‘organelles’, consume the sugars that our bodies have converted from food, and in return produce electricity with which to power the cell.  They are considered separate because they have their own DNA – DNA which is unaffected by other genetic exchanges.

mtDNA has special properties that make it an invaluable tool for genealogical and anthropological study. It mutates at a very slow rate, over tens of generations and thus can be used in long-range glimpses into the past. It is mtDNA that is used in estimating human migration patterns tens of thousands of years in the past and your DNA test will show which migration group and route you belong to!

HVR1 to 3 are located in the D-Loop shown above. HVR means ‘hyper variable region’ and this small area mutates faster than the rest of the circle and thus is great for genealogical studies. The rest of the circle is the Coding Region which a full genome test will reveal and here there is medical information as well. HVR1 results are usually enough to define your haplogroup, but too general for anything else.

For example, I am Haplogroup I (yes, like the site name :)). It is a European haplogroup (one of the first) and estimated to be about 35,000 years old originating in Iran (some places say), or from the Balkans. It’s not terribly exact, but it does give us a general idea of time and place.

Mutations do occur over time, and those are then passed down to the children - a DNA family tree of women only. These small changes allow scientists to study them as related to geographic areas, populations, and migrations. By tracing the mutations, we have an idea of ancient migration patterns.

mtDNA also lasts a very long time. That is how 5,000 year old skeletons are studied. Same with England’s 9,000 year old Cheddar Man who was linked to a local teacher in the present! Lucky guy - he has documented proof of a 9,000 year old ancestor! No great family photos though…

While both men and women have mitochondrial DNA (and can be tested for it), it is only passed along female lines. Unlike nuclear DNA, mtDNA is not divided during cell division. It simply gets copied from mother to child and passes down through the mother’s lineage, so this particular DNA family tree shows the link to your mother, her mother, her mother, and hers, and hers, and all the way back thousands of years. Any ‘matches” you may find indicate a common female ancestor in the distant past — and it means a lot of new relatives!

If a mutation occurs, it is then copied for generations forward. Those mutations are signposts along the historical and anthropological record and enable scientists to date population settlements and thus movements of peoples.

Ancestry DNA testing for genealogical purposes is growing in popularity, but the bigger the databases, the more matches we will find. We need more people putting their results into the searchable databases. So get out there (on the Web) and test! The DNA test is painless and the only hard part about it waiting for the results! Personally, I have used and recommend FTDNA (Family Tree DNA).

Don’t forget to post your Hg I results here!

graphic courtesy of DNA Heritage

Links:
mtDNA Mutation Rates: Studies vary widely as to the real age significance of mutations.
Upsetting Pet Theories: Mutation rates might be faster than previously thought.

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